| From 261ee33e0e6711fadd3049e4640bb731ee3d44ff Mon Sep 17 00:00:00 2001 |
| From: Kevin Wolf <kwolf@redhat.com> |
| Date: Mon, 24 Feb 2020 16:57:10 +0000 |
| Subject: [PATCH 9/9] mirror: Don't let an operation wait for itself |
| |
| RH-Author: Kevin Wolf <kwolf@redhat.com> |
| Message-id: <20200224165710.4830-3-kwolf@redhat.com> |
| Patchwork-id: 94045 |
| O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH 2/2] mirror: Don't let an operation wait for itself |
| Bugzilla: 1794692 |
| RH-Acked-by: John Snow <jsnow@redhat.com> |
| RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com> |
| RH-Acked-by: Max Reitz <mreitz@redhat.com> |
| |
| mirror_wait_for_free_in_flight_slot() just picks a random operation to |
| wait for. However, when mirror_co_read() waits for free slots, its |
| MirrorOp is already in s->ops_in_flight, so if not enough slots are |
| immediately available, an operation can end up waiting for itself to |
| complete, which results in a hang. |
| |
| Fix this by passing the current MirrorOp and skipping this operation |
| when picking an operation to wait for. |
| |
| Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1794692 |
| Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
| Reviewed-by: Eric Blake <eblake@redhat.com> |
| (cherry picked from commit 7e6c4ff792734e196c8ca82564c56b5e7c6288ca) |
| Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
| Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com> |
| |
| block/mirror.c | 21 ++++++++++++--------- |
| 1 file changed, 12 insertions(+), 9 deletions(-) |
| |
| diff --git a/block/mirror.c b/block/mirror.c |
| index 8959e42..cacbc70 100644 |
| |
| |
| @@ -283,11 +283,14 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, |
| } |
| |
| static inline void coroutine_fn |
| -mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) |
| +mirror_wait_for_any_operation(MirrorBlockJob *s, MirrorOp *self, bool active) |
| { |
| MirrorOp *op; |
| |
| QTAILQ_FOREACH(op, &s->ops_in_flight, next) { |
| + if (self == op) { |
| + continue; |
| + } |
| /* Do not wait on pseudo ops, because it may in turn wait on |
| * some other operation to start, which may in fact be the |
| * caller of this function. Since there is only one pseudo op |
| @@ -302,10 +305,10 @@ mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) |
| } |
| |
| static inline void coroutine_fn |
| -mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) |
| +mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s, MirrorOp *self) |
| { |
| /* Only non-active operations use up in-flight slots */ |
| - mirror_wait_for_any_operation(s, false); |
| + mirror_wait_for_any_operation(s, self, false); |
| } |
| |
| /* Perform a mirror copy operation. |
| @@ -348,7 +351,7 @@ static void coroutine_fn mirror_co_read(void *opaque) |
| |
| while (s->buf_free_count < nb_chunks) { |
| trace_mirror_yield_in_flight(s, op->offset, s->in_flight); |
| - mirror_wait_for_free_in_flight_slot(s); |
| + mirror_wait_for_free_in_flight_slot(s, op); |
| } |
| |
| /* Now make a QEMUIOVector taking enough granularity-sized chunks |
| @@ -555,7 +558,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) |
| |
| while (s->in_flight >= MAX_IN_FLIGHT) { |
| trace_mirror_yield_in_flight(s, offset, s->in_flight); |
| - mirror_wait_for_free_in_flight_slot(s); |
| + mirror_wait_for_free_in_flight_slot(s, pseudo_op); |
| } |
| |
| if (s->ret < 0) { |
| @@ -609,7 +612,7 @@ static void mirror_free_init(MirrorBlockJob *s) |
| static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) |
| { |
| while (s->in_flight > 0) { |
| - mirror_wait_for_free_in_flight_slot(s); |
| + mirror_wait_for_free_in_flight_slot(s, NULL); |
| } |
| } |
| |
| @@ -794,7 +797,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) |
| if (s->in_flight >= MAX_IN_FLIGHT) { |
| trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, |
| s->in_flight); |
| - mirror_wait_for_free_in_flight_slot(s); |
| + mirror_wait_for_free_in_flight_slot(s, NULL); |
| continue; |
| } |
| |
| @@ -947,7 +950,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) |
| /* Do not start passive operations while there are active |
| * writes in progress */ |
| while (s->in_active_write_counter) { |
| - mirror_wait_for_any_operation(s, true); |
| + mirror_wait_for_any_operation(s, NULL, true); |
| } |
| |
| if (s->ret < 0) { |
| @@ -973,7 +976,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) |
| if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || |
| (cnt == 0 && s->in_flight > 0)) { |
| trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); |
| - mirror_wait_for_free_in_flight_slot(s); |
| + mirror_wait_for_free_in_flight_slot(s, NULL); |
| continue; |
| } else if (cnt != 0) { |
| delay_ns = mirror_iteration(s); |
| -- |
| 1.8.3.1 |
| |